Wow thats crazy not welded to the frame. Got pics of attachment?
No pics unfortunately. I lost a bunch of pics to photo bucket and a dead PC.
In did similar to
@jcardona1 but I used 2 pieces of 3x3" hollow section, cut the face out of the rockers, unstitched the door thresholds and stitch welded the 3x3 in place, I kept the structure of the body in place on the backside of the rockers, and welded the hollow section there too.
There is a fair bit of structure in the rockers and where the pillars connect to them. I kept as much of that in place as possible, and welded everywhere I could before welding door thresholds back in.
In used 2 pieces of 3x3 because it gave me a double thickness where they butted together in the centre, so more vertical structure under the pillars.
I cut and welded the outer piece of 3x3 to taper the bottom edge
Mine copped some decent hits from slipping a wheel of a rock, and having the body drop onto a rock hard. I dented the underside of these, but had no sign of damage to the body or mounts etc
I reduced the depth of the seam under the rockers quite a bit, plus eliminated having sliders below the rocker, and had less connected to the frame to get hung up on. I tapered the outer bottom edge up to increase clearance more, and added the as a step.
I spent a day fabbing the SHS, and a full weekend cutting and welding on the body
I wasn't 100% sure how it was going to go until I hacked into it, once I got into it, it came together well.
I did this on mine when it was still looking quite presentable. Buddies spun out at me cutting into a tidy 105 series.